Reflective road markers for lanes and highways are very old and the problem of designing them so that they cannot interfere with the plowing of snow has been recognized for a long time. Two general approaches have been followed. One is to make them low enough and guarded by protection structures so that snowplows can jump over them, and the second is to make them plastic so they can retract, or give, when hit by a snowplow.
The state of the art of roadway markers which do not form a smooth surface which is a part of the surface of the roadway, is described in the publication entitled "State of the Art on Roadway Delineation Systems", "Prepared for Department of Transportation, Federal Highway Administration, Offices of Research & Development, Washington, D.C. 20590, Report No. FHWA-RD-76-73". Such roadway markers have a short life.
U.S. Pat. No. 2,329,171 to Russ, entitled HIGHWAY MARKER, issued Dec. 7, 1943, discloses a lane marker for roadways which is part of, and does not extend above, the surface of the roadway, but it fails to reflect adequate, if any, light from the headlight of an automobile back to the driver of that automobile.
The principal object of this invention is to provide a marker for roadways that provides adequate reflection of the light from an automobile headlight back to the driver of the automobile.
Another object of the invention is to provide an efficient low cost marker for roadways, that is easy to install, and does not interfere with a snowplow.
Still another object of the invention is to provide a satisfactory roadway marker having long life, to thus reduce the expense of frequent replacement.